It is well known in treating pneumothorax and other conditions of the pleural cavity that it is essential to remove excess fluids, blood and gases, such as air, from the pleural space between the lung and the surrounding rib cage. Fluids may accumulate in the space between the lung and the chest wall as the result of surgery, wounds, or infections. In such situations, it is essential to the patient's survival that any excess fluids or gases be removed from the pleural cavity of the patient in order to maintain the lung in its expanded state.
The typical chest drainage device is generally known as a three-bottle system which includes a collection chamber, a water seal chamber and a suction control or manometer chamber. For example, if the vacuum source applies 35 cm H.sub.2 O (source suction) and the desired vacuum pressure to the patient is 20 cm H.sub.2 O, liquid will be added to the suction control chamber until the liquid reaches a line indicating the desired 20 cm H.sub.2 O vacuum pressure. Atmospheric air bubbles into the suction control chamber through the liquid to offset the excess vacuum pressure from the vacuum source to create a vacuum pressure of 20 cm H.sub.2 O at the pleural cavity of the patient. During operation of these devices, atmospheric air is drawn into the suction control chamber through a first column and bubbles through the liquid in the bottom of the suction control chamber. The liquid level in the suction control chamber determines the actual amount of vacuum pressure being applied to the pleural cavity of the patient.
The chest drainage devices operate by drawing excess fluids and gases from the pleural cavity of the patient at the prescribed vacuum pressure. The excess fluid is collected in the collection chamber while the excess gases flow through the water seal chamber and into the vacuum source. The background and operation of chest drainage devices is discussed in more fully in U.S. Pat. No. 4,439,190, issued to Protzmann et al on Mar. 27, 1984 which is incorporated herein by reference.
One problem commonly associated with currently available chest drainage devices, is that as the atmospheric air is drawn into the bottom of the suction control chamber, the air bubbles violently through the liquid present in the bottom of the suction control chamber. The noise associated with this bubbling is frequently annoying to both the patient and the physician. Additionally, when this bubbling occurs at higher vacuum pressures, the bubbling may actually cause fluxuations in the amount of vacuum pressure being applied to the pleural cavity of the patient. Furthermore, under certain circumstances this violent bubbling at higher vacuum pressures may cause the liquid from the suction control chamber to be drawn into the vacuum source.
U.S. Pat. No. 3,782,497 issued to Bidwell et al on Jan. 1, 1974 discloses a sound muffling device which consists essentially of a plug-like member which is inserted into the top of the suction control chamber. This member is provided with a tortuous passageway therethrough in order to muffle the sound emanating from the device caused by the atmospheric air as it bubbles through the liquid in the suction control chamber.
Another approach is illustrated in U.S. Pat. No. 4,601,715 issued to Olson on July 22, 1986. This device consists of an elongate tube which is inserted into the first column of the suction control chamber. As the atmospheric air enters the suction control chamber, the elongate tube vibrates to dissipate the noise caused by the atmospheric air as it bubbles through the liquid in the suction control chamber.
Yet another approach is illustrated in U.S. Pat. No. 4,439,190 issued to Protzmann et al on Mar. 27, 1984. This device includes a foot member which is attached to the bottom of the first column in the suction control chamber. The foot member includes an enlarged end having a plurality of relatively small openings therein to cause the air bubbles to follow a circular path through the liquid in the suction control chamber.
Despite these and other chest drainage devices which are designed to decrease or muffle the noise caused by the atmospheric air as it bubbles through the suction control chamber, a need remains for an improved suction control chamber which will operate quietly and provide an accurate measurement of the amount of suction pressure actually being applied to the pleural cavity of the patient. Additionally, a need remains for a suction control chamber which will decrease the likelihood that liquid from the suction control chamber will be drawn into the vacuum source at higher vacuum pressures.